This invention relates to apparatus and method for emptying liquid filled bladder type mattresses such as waterbed mattresses adapted to suppress undesired fluid wave motion by the inclusion of wave dampening means composed of foam, fiber or the like. More particularly, this invention relates to a system comprising elongated perforated pipes inserted into a waterbed mattress thereby increasing the rate with which such a mattress is emptied.
A number of types of waterbed mattresses and other flotation systems have been developed which have the capacity to suppress or dampen liquid wave motion. This liquid wave dampening has been achieved in some cases by the inclusion of a core of material such as fiber or foam inside the mattresses.
For example, in U.S. Pat. No. 3,585,356, issued to C. Hall discloses the use of ground, shredded, or blocks of expanded cellular styrene in a waterbed mattress to produce a wave dampening effect.
Fraige, U.S. Pat. No. 4,301,560, discloses the use of non-woven or very loosely woven expanded fiber product in a waterbed mattress to dampen wave motion.
A presently pending application by Morgan, Ser. No. 191,169, now U.S. Pat. No. 4,411,033 which has been assigned to the assignee of the present application, discloses a waterbed mattress having a slab of substantially open-celled foam or cellulosic sponge disposed in the waterbed mattress.
The use of the materials such as those described above for dampening wave motion in waterbed systems has created a difficult draining problem. Often it becomes necessary to remove the liquid from a filled mattress in order to move the waterbed or to service leaks in the mattress. A king size mattress, for example, contains about 1600 to 2000 pounds of water, depending on the degree of fill. Small units contain lesser amounts of water, although the problem of draining the mattress is still severe.
A waterbed mattress may be drained using various means such as a siphon or pump. The most common pump is the Venturi type, which may be operated on most household water spigots. A Venturi pump will drain a regular king size mattress in 40 to 50 minutes. However a king size mattress containing foam or fiber fill requires several hours to be drained using a Venturi pump and is generally still too heavy to be handled by an individual of ordinary strength. The problem of draining and moving a wave dampening material-filled waterbed has caused consumer resistance to the sale of this product.
Draining of a waterbed mattress containing wave dampening material is so slow for two principal reasons. First, the encapsulation in the interstices of the foam or fiber greatly slows the movement of the water to the drain port. Second, water flows through the drain port area faster than it flows from the wave dampening material, thereby creating a vacuum which at least partially collapses the drain port and the area around it. As a result, the drain port is sealed against further draining or, at least closed so as to restrict flow therethrough.